Composite composition of inorganic oxide particles and silicone resin, method of manufacturing the same, transparent composite, and method of manufacturing the same

ABSTRACT

A method of manufacturing a composite composition, having: bonding a dispersant to the surfaces of inorganic oxide particles to provide dispersibility in a hydrophobic solvent to the inorganic oxide particles, and then dispersing the inorganic oxide particles in a hydrophobic solvent; substituting the dispersant bonded to the surfaces of the inorganic oxide particles with a surface modifier, which is a polydimethylsiloxane-skeleton polymer having one functional group at one terminal end, in the hydrophobic solvent in which the organic oxide particles are dispersed to bond the functional group of the polydimethylsiloxane-skeleton polymer to the surfaces of the inorganic oxide particles; and conjugating a silicone resin and the inorganic oxide particles obtained in the previous step, wherein the surface thereof is modified by bonding the polydimethylsiloxane-skeleton polymer having one functional group at one terminal end thereof, to obtain a composite composition.

TECHNICAL FIELD

The present invention relates to a composite composition of inorganicoxide particles and a silicone resin, a method of manufacturing thesame, a transparent composite, and a method of manufacturing the same.

Priority is claimed based on Japanese Patent Application No.2010-161990, filed on Jul. 16, 2010, and the contents thereof areincorporated herein by reference.

BACKGROUND ART

Thus far, attempts have been made to improve the mechanicalcharacteristics and the like of a resin by conjugating (mixing) aninorganic oxide, such as silica, as a filler and the resin. An ordinarymethod of conjugating the filler and the resin is a method in which adispersion fluid containing the inorganic oxide dispersed in water or anorganic solvent and the resin or resin raw material components aremixed. It is possible to manufacture metal oxide particle-conjugatedplastic in which inorganic oxide particles are conjugated in a resin bymixing a dispersion fluid, the resin and the like by a variety ofmethods as a second phase (for example, refer to Patent Literature 1).

Among resins, silicone resins are used in a wide range from cosmeticmaterials or biomedical materials to electrical or electronic materialsdue to their excellent weather resistance characteristics, such as heatresistance and cold resistance, excellent electrical characteristics,low toxicity, and the like. In addition, recently, attention has beengiven to their transparency, and thus silicone resins have been used inoptical members, such as a transparent sealing material and the like ofa light-emitting diode. The optical members need to have properties,such as optical characteristics such as transparency and refractiveindex, mechanical characteristics such as hardness, and thermalstability such as heat resistance.

Generally, in a case in which a resin and an inorganic material such asan inorganic oxide are conjugated so as to obtain a composite, a varietyof methods in which the compatibility between an inorganic material anda resin is improved by modifying the surface of the inorganic material,or previously conjugated raw materials are polymerized so as to obtain acomposite are used.

For example, in a case in which inorganic oxide particles are conjugatedwith a hydrophobic resin, since the surfaces of the inorganic oxideparticles are hydrophilic at all times, there was a problem that theinorganic oxide particles are not easily dispersed in the hydrophobicresin. Therefore, as a general solution, efforts have been made to makethe surfaces of the inorganic oxide particles hydrophobic and increasethe compatibility between the resin and the inorganic oxide particles byadding a surface modifier, such as an organic polymer dispersant, to thesurfaces of the inorganic oxide particles.

However, in a case in which a silicone resin is selected as the resin,the silicone resin is highly hydrophobic. Therefore, it is difficult tomake the surfaces of the inorganic oxide particles hydrophobic until theinorganic oxide particles are dissolved together with the siliconeresin, which creates a problem that the silicone resin and the inorganicoxide particles are separated, and it is difficult to conjugate thesilicone resin and the inorganic oxide particles.

Therefore, in order to conjugate the silicone resin and the inorganicoxide particles so as to obtain a conjugated plastic having favorableoptical characteristics or thermal stability, for example, a compositionin which zirconium oxide particles are conjugated with a hydroxylgroup-containing polysiloxane in the presence of a chelating agent isproposed (Patent Literature 2).

In addition, a composition for coating light-emitting elements in whichzirconium oxide particles and a polyfunctional polysiloxane areconjugated is also proposed (Patent Literature 3).

PRIOR ART DOCUMENTS Patent Literature

-   -   Patent Literature 1: Japanese Unexamined Patent Publication No.        2005-161111    -   Patent Literature 2: Japanese Unexamined Patent Publication No.        2006-316264    -   Patent Literature 3: Japanese Unexamined Patent Publication No.        2009-091380

SUMMARY OF INVENTION Problems to be Solved by the Invention

However, as described in Patent literature 2, in a case in whichinorganic oxide particles and a silicone resin are dissolved in togetherby a chelating agent, there was a problem that the obtained compositecomposition or conjugated plastic is colored due to aging deteriorationor thermal degradation which is caused particularly by modification of achelating agent.

In addition, in a case in which a hydroxyl group-containing polysiloxaneis used, since water is generated as the polysiloxane and the siliconeresin are crosslinked with each other, there was a likelihood of adisadvantage that, in some cases, the phase separation of the inorganicoxide particles and the polysiloxane is caused due to water, or pores(micropores) or cracks (slit) are generated in the conjugated plasticdue to dehydration-induced volume shrinkage.

Furthermore, as described in Patent literature 3, in a case in which apolyfunctional polysiloxane is used, there is a limitation in blendingthe inorganic oxide particles and the polysiloxane due to thecompatibility thereof and the like, and, particularly, in a case inwhich the amount of the inorganic oxide particles is large, there was aproblem that pores or cracks are significantly generated in theconjugated plastic.

Furthermore, in the respective Patent literature, since the particlediameter of the inorganic oxide particles is as large as 20 nm or more,there was a problem that the transparency deteriorates, and theconjugated plastic becomes opaque in some cases.

Means for Solving the Problem

The invention has been made in consideration of the above circumstances.That is, an object of the invention is to provide a compositecomposition of a silicone resin and inorganic oxide particles, atransparent composite and methods of manufacturing the same, wherein thecomposition has excellent optical characteristics, mechanicalcharacteristics and thermal stability, and the silicone resin and theinorganic oxide particles are favorably conjugated, that is, theinorganic oxide particles are uniformly dispersed in and integrated withthe silicone resin without any problem, so that phase separation doesnot occur, neither pores or cracks are generated, and coloration isprevented.

As a result of intensive studies to solve the above problems, thepresent inventors found that, when a specific method is used as a methodof modifying the surfaces of inorganic oxide particles using a surfacemodifier composed of a polydimethylsiloxane-skeleton polymer having onefunctional group at one terminal end, the surface modifier is favorablyintroduced into the surfaces of the inorganic oxide particles, and,consequently, a favorable composite composition can be obtained. Thatis, it was found that, when a dispersant is bonded to the surfaces ofthe inorganic oxide particles in advance so as to provide dispersibilityin a hydrophobic solvent, then, the inorganic oxide particles aredispersed in the hydrophobic solvent, and the dispersant is exchangedwith the surface modifier composed of a polydimethylsiloxane-skeletonpolymer having one functional group at one terminal end, resulting inthe surface modifier composed of a polydimethylsiloxane-skeleton polymerhaving one functional group at one terminal end being favorablyintroduced into the surfaces of the inorganic oxide particles. Inaddition, it was found that a favorable composite composition can beobtained by conjugating inorganic oxide particles which include anintroduced surface modifier using the above method and have an averagedispersed particle diameter of 1 nm to 20 nm and a silicone resin.

Furthermore, it was found that, when the surfaces of inorganic oxideparticles having an average dispersed particle diameter of 1 nm to 20 nmare modified using a surface modifier composed of apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end, the compatibility of the inorganic oxide particles withrespect to the silicone resin is significantly improved, and a favorablecomposite composition of the silicone resin and the inorganic oxideparticles can be obtained. In addition, it was found that a transparentcomposite which is a conjugated plastic formed by curing the abovecomposite composition, not only maintains the heat resistance and lightresistance of the silicone resin but also obtains excellent opticalcharacteristics, mechanical characteristics, and thermal stability dueto conjugation with the inorganic oxide particles. The above findingleads to a completion of the invention.

That is, a first aspect of the invention is a method of manufacturing acomposite composition, comprising:

bonding a dispersant to the surfaces of inorganic oxide particles toprovide dispersibility in a hydrophobic solvent to the inorganic oxideparticles, and then dispersing the inorganic oxide particles in ahydrophobic solvent;

substituting the dispersant bonded to the surfaces of the inorganicoxide particles and a surface modifier, which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof, in the hydrophobic solvent in which the organicoxide particles are dispersed to bond the functional group of thepolydimethylsiloxane-skeleton polymer to the surfaces of the inorganicoxide particles; and

conjugating a silicone resin and the inorganic oxide particles obtainedin the previous step, wherein the surface thereof is modified by bondingthe polydimethylsiloxane-skeleton polymer having one functional group atone terminal end thereof, to obtain a composite composition.

The surface modifier preferably includes one or two kind selected frommonoglycidyl ether-terminated polydimethylsiloxane and monohydroxyether-terminated polydimethylsiloxane.

The specific dispersant which is used to be bonded to the surfaces ofthe inorganic oxide particles is preferably an organic acid compound oran organic base compound.

The silicone resin is preferably a straight silicone resin or a modifiedsilicone resin.

In addition, a second aspect of the invention is a composite compositioncontaining inorganic oxide particles having an average dispersedparticle diameter of 1 nm to 20 nm and a silicone resin, in which onefunctional group of a surface modifier composed of apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end is bonded to the surfaces of the inorganic oxide particlesto modify the surfaces.

A third aspect of the invention is a transparent composite, whereininorganic oxide particles having an average dispersed particle diameterof 1 nm to 20 nm is dispersed in a silicone resin, and

the surface of the inorganic oxide particle is modified by bonding onefunctional group of a surface modifier, which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof is bonded, to the surfaces of the inorganic oxideparticles.

A fourth aspect of the invention is a method of manufacturing atransparent composite by molding and solidifying the compositecomposition of the invention.

Effects of Invention

According to the composite composition of the invention, since thecomposite composition contains inorganic oxide particles having anaverage dispersed particle diameter of 1 nm to 20 nm and a siliconeresin, and the inorganic oxide particles are modified by bonding afunctional group of a surface modifier which is apolydimethylsiloxane-skeleton polymer having the functional group at oneterminal end thereof to the surfaces of the inorganic oxide particles,the compatibility between the inorganic oxide particles and the siliconeresin is high, the conjugating properties of the two are excellent, andthe coloration is prevented.

Furthermore, a transparent composite obtained by molding and solidifyingthe composite composition in a specific shape has a high compatibilitybetween the inorganic oxide particles and the silicone resin. Therefore,since the inorganic oxide particles are favorably dispersed in thesilicone resin without being agglomerated, it is possible to obtain acomposite having excellent optical characteristics, mechanicalcharacteristics and thermal stability.

In addition, since the inorganic oxide particles are made intonanoparticles having an average dispersed particle diameter of 1 nm to20 nm, particularly, the transparency is excellent. Therefore, in thetransparent composite obtained by molding and solidifying the compositecomposition in a specific shape, it is possible to obtain a compositehaving excellent transparency.

According to the method of manufacturing a composite composition of theinvention, a specific dispersant is bonded to the surfaces of inorganicoxide particles in advance so as to provide dispersibility in ahydrophobic solvent, and then the inorganic oxide particles aredispersed in the hydrophobic solvent. Next, the specific dispersantbonded in advance to the surfaces of the inorganic oxide particles issubstituted with a surface modifier composed of apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof in the hydrophobic solvent. Using the above steps,the functional group of the surface modifier which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof is bonded to the surfaces of the inorganic oxideparticles. After that, the silicone resin and the inorganic oxideparticles obtained in the above step are conjugated, wherein theinorganic oxide particles have been modified at the surfaces thereofthrough bonding of the polydimethylsiloxane-skeleton polymer having onefunctional group at one terminal end thereof. Since the above method isused, inorganic oxide particles which have an excellent compatibilitywith the silicone resin and substantially have no unreacted functionalgroup of the surface modifier are obtained first, and then it ispossible to conjugate the inorganic oxide particles and the siliconeresin. Therefore, it is possible to obtain a composite which hasexcellent conjugating properties between the inorganic oxide particlesand the silicone resin, and has excellent optical characteristics,mechanical characteristics, and thermal stability.

The transparent composite of the invention is a transparent compositehaving a specific shape in which inorganic oxide particles having anaverage dispersed particle diameter of 1 nm to 20 nm are dispersed in asilicone resin, and the surfaces of the inorganic oxide particles aremodified through bonding of a functional group of a surface modifierwhich is a polydimethylsiloxane-skeleton polymer having one functionalgroup at one terminal end thereof. Therefore, it is possible to obtain atransparent composite in which the dispersibility of inorganic oxideparticles in a silicone resin is excellent, pores or cracks are notgenerated, and optical characteristics such as transparency ormechanical characteristics and thermal stability are excellent.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention relates to a conjugated composition of inorganic oxideparticles and a silicone resin, a method of manufacturing the same, atransparent composite, and a method of manufacturing the same. Morespecifically, the invention relates to a composite compositionconjugated by treating inorganic oxide particles which are preferablyused as a filler material of a silicone resin, and enable not onlyimprovement of the refractive index and the mechanical characteristicsbut also maintenance of the transparency using a specific method andimproving the compatibility of the inorganic oxide particles in thesilicone resin, and a method of manufacturing the same, a transparentcomposite, and a method of manufacturing the same.

Hereinafter, an embodiment of a composite composition of inorganic oxideparticles and a silicone resin, which is an embodiment of the invention,and an embodiment for carrying out a method of manufacturing thecomposite composition of inorganic oxide particles and a silicone resin,which is an embodiment of the invention, will be described.

Meanwhile, the embodiments are descriptions of specific examples foreasier understanding of the purport of the invention, and do not limitthe invention unless otherwise described.

Addition, omission, substitution, and other variations are permittedwithin the scope of the purport of the invention. The invention is notlimited by the following descriptions, and is limited only by the scopeof the attached claims.

[Composite Composition]

The composite composition of the present embodiment is a compositecomposition containing inorganic oxide particles having an averagedispersed particle diameter of 1 nm to 20 nm and a silicone resin, inwhich the surfaces of the inorganic oxide particles are modified throughbonding of a functional group of a surface modifier which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof.

Here, the “composite composition” represents a composition which doesnot have a specific shape, has an irreversible deformability which doesnot allow returning to the original shape once deformed (changed), andserves as a raw material of a transparent composite described below.That is, the composite composition indicates, for example, a compositionin a state of a liquid phase or a gel phase having a thixotropy nature.Conversely, the “transparent composite” described below refers to acomposite which can maintain a constant shape in accordance with thepurpose or method of use, and examples thereof include a composite in anordinary solid phase which substantially does not have a deformability,a composite having an elastic deformability (shape-returning properties)such as rubber, and the like.

The inorganic oxide particles are not particularly limited, and examplesthereof that can be used include oxides of elements such as zirconia(Zr), titanium (Ti), silicon (Si), aluminum (Al), iron (Fe), copper(Cu), zinc (Zn), yttrium (Y), niobium (Nb), molybdenum (Mo), indium(In), tin (Sn), tantalum (Ta), tungsten (W), lead (Pb), bismuth (Bi),cerium (Ce), antimony (Sb) and germanium (Ge).

Examples of the oxides of these elements include zirconium oxide (ZrO₂),titanium oxide (TiO₂), silicon oxide (SiO₂), aluminum oxide (Al₂O₃),iron oxide (Fe₂O₃, FeO, Fe₃O₄), copper oxide (CuO, Cu₂O), zinc oxide(ZnO), yttrium oxide (Y₂O₃), niobium oxide (Nb₂O₅), molybdenum oxide(MoO₃), indium oxide (In₂O₃, In₂O), tin oxide (SnO₂), tantalum oxide(Ta₂O₅), tungsten oxide (W^(O) ₃, W₂O₅), lead oxide (PbO, PbO₂), bismuthoxide (Bi₂O₃), cerium oxide (CeO₂, Ce₂O₃), antimony oxide (Sb₂O₃,Sb₂O₅), germanium oxide (GeO₂, GeO), and the like.

In addition, the inorganic oxide particles may be a composite oxide suchas tin-doped indium oxide (ITO) or yttria-stabilized zirconia (YSZ).Particularly, in a case in which a composite composition with a siliconeresin is made to have a high refractive index, it is possible topreferably use zirconium oxide (ZrO₂) or titanium oxide (TiO₂) which hasa high refractive index, is colorless and transparent, and has a highhardness.

The average dispersed particle diameter of the inorganic oxide particlesin the composite composition or a transparent composite obtained fromthe composite composition is preferably 1 nm to 20 nm.

Here, the reason for limiting the average dispersed particle diameter to1 nm to 20 nm is that, when the average dispersed particle diameter isless than 1 nm, the primary particle diameter of particles that formsthe dispersed particles also becomes less than 1 nm such that thecrystallinity becomes insufficient, and it becomes difficult to expressparticle characteristics such as the refractive index. On the otherhand, when the average dispersed particle diameter exceeds 20 nm, theinfluences of Rayleigh scattering become large, and the transparency ofthe composite composition or the transparent composite deteriorates.

As such, since the inorganic oxide particles are nanometer-sizedparticles, even in a case in which the inorganic oxide particles aredispersed in a silicone resin so as to produce a composite compositionor a transparent composite, light scattering is small, and it ispossible to maintain the transparency of the composite composition andthe transparent composite.

The surfaces of the inorganic oxide particles are modified using asurface modifier which is a polydimethylsiloxane-skeleton polymer havingone functional group at one terminal end. The surface modifier has apolydimethylsiloxane structure, particularly preferably a straight-chainpolydimethylsiloxane structure, as the main chain skeleton, and has onlyone polar group which is a functional group at one terminal end (one endside) of the main chain. That is, there is no polar group at the otherterminal end (the other end) of the main chain. Therefore, when thefunctional group (polar group) is selectively bonded to the surfaces ofthe inorganic oxide particles, the other end side, that is, the siloxaneskeleton portion, which is a portion other than the functional group,forms a shape facing the outside of the particles (in a direction ofgetting away from the surfaces of the inorganic oxide particles) so thatall siloxane skeleton portions face the outside. Since the siloxanestructure portions and the silicone resin have a high compatibility, andalso have a favorable affinity, it is possible to uniformly disperse theinorganic oxide particles in the silicone resin, and to form a favorablecomposite composition. Meanwhile, here, the “straight-chain” means thatthere is no branch (ramification) in the polydimethylsiloxane skeleton.

On the other hand, in a case in which there are branches (ramifications)in the siloxane skeleton, or the functional group is located in themiddle of the siloxane skeleton (the functional group is bonded tosilicon located in the middle of the siloxane structure), at least apart of the siloxane skeleton does not face in a direction of gettingaway from the surfaces of the inorganic oxide particles, and is liableto have a locational relationship in which apart of the siloxanestructure faces in a direction toward the surfaces of the particles oris parallel to the surfaces of the particles. In this case, compared toa case in which the surface modifier composed of a straight-chainpolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end is used, the amount of the siloxane structure facing theoutside of the inorganic oxide particles decreases, and, consequently,there is a possibility that the compatibility or affinity maydeteriorate between the inorganic oxide particles and the siliconeresin. Furthermore, compared to a case in which the surface modifiercomposed of a straight-chain polydimethylsiloxane-skeleton polymerhaving one functional group at one terminal end is used, the uniformityin the direction of the siloxane skeleton is low, there is a possibilitythat entanglement or steric hindrance may occur between the siloxanestructures, and there is a possibility that the compatibility oraffinity may deteriorate between the inorganic oxide particles and thesilicone resin.

In addition, since the surface modifier has one functional group and thefunctional group is used for bonding with the inorganic oxide particle,there is no unreacted functional group in the surface modifier which hasbeen bonded to the inorganic oxide particles. Therefore, there is nopossibility that deterioration of the compatibility with the siliconeresin occurs, such as a phenomenon of cloudy, wherein such deteriorationis caused by unreacted functional groups which are remained in a case inwhich a polyfunctional polysiloxane of the related art is used.Accordingly, it is possible to obtain a stabilized complex composition.

The surface modifier preferably includes one or two kinds selected from,for example, monoglycidyl ether-terminated polydimethylsiloxane andmonohydroxy ether-terminated polydimethylsiloxane.

Among examples of terminal end groups of thepolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end, which is the surface modifier, in the case of themonoglycidyl ether-terminal end, the epoxide portion which is a part ofthe glycidyl group thereof is ring-opened and bonds with the hydroxylgroup on the surfaces of the inorganic oxide particle. In addition, inthe case of the monohydroxy ether-terminal end, the hydroxyl groupexisting at the terminal end thereof bonds with the hydroxyl groupexisting on the surfaces of the inorganic oxide particles by dehydrationcondensation.

In examples of the surface modifier, the monoglycidyl ether-terminatedpolydimethylsiloxane originally contains no hydroxyl group, and themonohydroxy ether-terminated polydimethylsiloxane has only one hydroxylgroup, which is a functional group that bonds with the inorganic oxideparticle. Therefore, both surface modifiers do not have hydroxyl groupsafter being bonded to the surfaces of the inorganic oxide particles.Therefore, water is not generated as a result of a dehydration reaction,even when the composite composition is cured by a crosslinking reactionbetween polysiloxane of the surface modifier and the silicone resin, forexample, even when the composite composition is cured by a crosslinkingreaction which is caused by a dehydrogenation reaction, using a peroxideas a catalyst, between a methyl group (—CH₃) bonding to Si of apolysiloxane and a methyl group bonding to Si of the silicone resin.Therefore, there is no problem caused by water being generated. Inaddition, a transparent composite obtained in the above manner has asmall shrinkage rate. Therefore, since pores or cracks are not generatedin the transparent composite, and the dispersibility of the inorganicoxide particles in the cured silicone resin is favorably maintained, itis possible to obtain a defect-free transparent composite.

In the embodiment, the surfaces of the inorganic oxide particles can bemodified so that the surface is suitable for improving the compatibilityor dispersibility with respect to the silicone resin. Therefore, thereis no particular limitation in the silicone resin, and an ordinarysilicone resin can be used without any problem. Among silicone resinsthat can be used in the embodiment, particularly, a straight siliconeresin or a modified silicone resin can be preferably used. Here, the“straight silicone resin” refers to a polymer (resin) in which a methylgroup, a phenyl group, and/or a hydrogen atom are bonded to thepolysiloxane skeleton as substituents. The “modified silicone resin”refers to a polymer obtained by secondarily bonding a functional groupto the straight silicone resin so as to provide a function.

The reason for preferably using the straight silicone resin is that thestraight silicone resin has no side chain and has a linear shape, andtherefore has excellent mixing properties with the inorganic oxideparticles. In addition, the reason why the modified silicone resin ispreferable is that the modified silicone resin has excellent reactivityor crosslinking properties due to a functional group introduced thereto.However, depending on the kind or amount of the introduced functionalgroup, there is a possibility that problems such as deterioration of thetransparency of the obtained transparent composite may occur, due to theinfluences of byproducts generated in a case in which the silicone resinis cured, the amount of the byproducts or the like. Therefore, there arecases in which attention needs to be paid in selecting the modifiedsilicone.

Examples of the straight silicone resin include a methyl silicone resin,a methyl phenyl silicone resin, and the like. In addition, examples ofthe modified silicone resin include an epoxy-modified silicone resin, anepoxy polyether-modified silicone resin, a carbinol-modified siliconeresin, a methacryl-modified silicone resin, a phenol-modified siliconeresin, a methyl styryl-modified silicone resin, an acryl-modifiedsilicone resin, a methyl hydrogen silicone resin, and the like. Thesilicone resin may be selected solely or used in combination of two ormore kinds.

Meanwhile, when the composite composition obtained by mixing thesilicone resin, inorganic oxide particles, and the like is a compositecomposition which does not have a specific shape, has an irreversibledeformability which does not allow returning to the original shape oncedeformed, for example, a characteristic of being present in a state of aliquid phase or a gel phase having a thixotropy nature, and is a rawmaterial of a transparent composite described below, the silicone resinis not particularly limited. Therefore, the degree of polymerization ofthe silicone resin is not particularly limited.

That is, when the composite composition has the above characteristics,the silicone resin may be any of a monomer (monomer), an oligomer (apolymer obtained by polymerizing approximately 2 to several hundredsthereof), and a polymer (a polymer obtained by polymerizing severalhundreds or more thereof). Furthermore, by combining the above, asubstance having a certain range of the polymerization degree may bealso used.

In addition, within the scope in which the characteristics thereof arenot impaired, an antioxidant, a release agent, a coupling agent, aninorganic filler, and the like may be added to the silicone resin.

The content of the inorganic oxide particles in the compositecomposition is preferably 1% by mass to 90% by mass, more preferably 5%by mass to 90% by mass, and still more preferably 10% by mass to 85% bymass.

The reason for limiting the content of the inorganic oxide particles inthe composite composition to 1% by mass to 90% by mass is as follows.That is, when the content is less than 1% by mass, since the amount ofthe inorganic oxide particles is too small, changes in the opticalcharacteristics or mechanical characteristics of the silicone resin,which are caused by conjugation of the inorganic oxide particles, arenot expressed. Therefore, there is no substantial effect of conjugatingthe inorganic oxide particles. On the other hand, when the contentexceeds 90% by mass, it becomes impossible to sufficiently secure thedispersibility of the inorganic oxide particles, the fluidity of thecomposite composition deteriorates, and the moldability deteriorates.

In the composite composition of the embodiment, it is possible to add ahydrophobic solvent in addition to the inorganic oxide particles and thesilicone resin.

The reasons why a hydrophobic solvent is added are as follows. First, ina case in which a mixture of the inorganic oxide particles and thesilicone resin has a high viscosity, the fluidity of the mixture becomespoor, and therefore, problems may be caused wherein the moldability ofthe transparent composite described below becomes poor or properties ofeasy handling becomes poor. In order to solve the problems, ahydrophobic solvent can be solved to decrease the viscosity of themixture. In addition, as described in the manufacturing method describedbelow, a method is preferable in terms of properties of easy mixing,wherein inorganic oxide particles modified using a surface modifier aredispersed again in a hydrophobic solvent having a high compatibilitywith a silicone resin which is used, and the fluid dispersion of theinorganic oxide particles and the silicone resin are mixed and stirred,thereby obtaining a composite composition.

The reason why a hydrophobic solvent is used as the solvent and issuitable for the method of the embodiment is that such a solventachieves suitable dispersibility of the surfaces treated inorganic oxideparticles, and has excellent compatibility with the silicone resin.

Examples of the hydrophobic solvent that can be preferably used includearomatic hydrocarbon such as benzene, toluene, xylene, and ethylbenzeneand chlorine-containing solvents such as dichloromethane, chloroform,and carbon tetrachloride. It is possible to use one or two or more ofthe solvents.

[Method of Manufacturing the Composite Composition]

In the method of manufacturing the composite composition of theembodiment, a specific dispersant is bonded in advance to the surfacesof inorganic oxide particles so as to provide a dispersibility in ahydrophobic solvent, and then the inorganic oxide particles aredispersed in a hydrophobic solvent. In addition, by substituting thespecific dispersant bonded in advance to the surfaces of the inorganicoxide particles with a surface modifier composed of apolydimethylsiloxane-skeleton polymer having the monofunctional group atone terminal end in the hydrophobic solvent, the functional group of thesurface modifier which is a polydimethylsiloxane-skeleton polymer havingone functional group at one terminal end thereof is bonded to thesurfaces of the inorganic oxide particles. After that, the obtainedinorganic oxide particles having the surfaces modified through bondingof the polydimethylsiloxane-skeleton polymer having one functional groupat one terminal end and the silicone resin are conjugated.

Hereinafter, the method of manufacturing the composite composition willbe described according to the manufacturing sequence.

In the method of manufacturing the composite composition of theembodiment, in the beginning, a specific dispersant is bonded in advanceto the surfaces of inorganic oxide particles so as to provide adispersibility in a hydrophobic solvent. The specific dispersant refersto a dispersant in which, in a case in which the inorganic oxideparticles to which the specific dispersant is bonded can be easilydispersed in a hydrophobic solvent, and a surface modifier composed of apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end is present together with the inorganic oxide particles towhich the specific dispersant is bonded, the specific dispersant bondedin advance to the particles can be easily substituted with the surfacemodifier on the surfaces of the inorganic oxide particles. The specificdispersant is not particularly limited as long as the dispersant has theabove properties, and an organic acid compound or an organic basecompound may be used.

Here, examples of the organic acid compound include carboxylic acid,phosphoric acid, sulfonic acid, and the like, examples of the organicbase compound include amine, phosphazene base, and the like, and thedispersant is appropriately selected based on the compatibility with theinorganic oxide particles.

Among the dispersants, a carboxylic acid or an amine is particularlypreferably used. As the carboxylic acid, one or two or more kindsselected from, for example, saturated fatty acids such as formic acid,acetic acid, butyric acid, valeric acid, caproic acid, enanthic acid,caprylic acid, capric acid, lauric acid and stearic acid, andunsaturated fatty acids such as oleic acid may be used. In addition, asthe amine, one or two or more kinds selected from, for example, aromaticamines such as pyridine and bipyridine, and aliphatic amines such astriethylamine, diethylamine, monoethylamine, and butylamine may be used.

The reason why the carboxylic acid or the amine is the preferably useddispersant is as follows.

Firstly, since the carboxylic acid or the amine can form a hydrogen bondwith the surfaces of the inorganic oxide particles, the carboxylic acidor the amine is easily bonded to the inorganic oxide particles as longas only the carboxylic acid or the amine is present. In addition, theobtained inorganic oxide particles having the carboxylic acid or theamine bonded to the surfaces can hold dispersion stability in ahydrophobic solvent due to the presence of the carboxylic acid or theamine.

Meanwhile, in a case in which a substance having a larger bondingproperties with respect to the inorganic oxide particles than thecarboxylic acid or the amine, that is, a surface modifier which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end is present, since the hydrogen bond between the inorganicoxide particles and the dispersant has a weak interaction, thecarboxylic acid or the amine rapidly detaches from the inorganic oxideparticles, and is substituted with the surface modifier.

For the above reasons, the carboxylic acid or the amine functions as adispersant that disperses the inorganic oxide particles, and can be madeto favorably detach during a reaction with the surface modifier, andtherefore the carboxylic acid or the amine can be preferably used as thespecific dispersant of the embodiment.

Next, the inorganic oxide particles having the specific dispersantbonded to the surfaces thereof are dispersed in a hydrophobic solvent.

Any solvent can be used as the hydrophobic solvent as long as theinorganic oxide particles are stably dispersed, and examples thereofinclude aromatic hydrocarbon such as benzene, toluene, xylene, andethylbenzene; and chlorine-containing solvents such as dichloromethane,chloroform, and carbon tetrachloride. It is possible to use one or twoor more kinds of the solvents.

Here, the reason for using the hydrophobic solvent is that favorableresults can be obtained when the surface modifier which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end is made to act on the inorganic oxide particles in thesubsequent process.

Examples of a specific method for bonding the specific dispersant to thesurfaces of the inorganic oxide particles so as to providedispersibility in the hydrophobic solvent and dispersing the inorganicoxide particles in the hydrophobic solvent include the following method.

Examples thereof include a method in which tetragonal zirconia particlesare used as the inorganic oxide particles, a hydrophobic solvent as adispersion medium and the carboxylic acid which serves as the specificdispersant are added to and mixed with the zirconia particles, and then,a dispersion treatment is carried out using a wet mixing method such asball milling or beads milling in which 0.05 mmφ to 1 mmφ zirconia beadsare used. Using the above method, a treatment of the tetragonal zirconiaparticles using the carboxylic acid is carried out at the same time asdispersion of the tetragonal zirconia particles in the hydrophobicsolvent, whereby a tetragonal zirconia dispersion fluid in which thecarboxylic acid is bonded (hydrogen bond) to the surfaces of theparticles can be prepared.

In addition, in a case in which silica (silicon oxide) is used as theinorganic oxide particles, amines are preferably selected, andbutylamine is particularly preferably selected, as the specificdispersant.

Next, a surface modifier which is a polydimethylsiloxane-skeletonpolymer having one functional group at one terminal end is added to thehydrophobic solvent in which the inorganic oxide particles are dispersedso as to substitute the surface modifier for the specific dispersantbonded in advance to the surfaces of the inorganic oxide particles,thereby bonding the surface modifier to the surfaces of the inorganicoxide particles so as to modify the surfaces.

The surface modifier preferably includes one or two kinds selected frommonoglycidyl ether-terminated polydimethylsiloxane and monohydroxyether-terminated polydimethylsiloxane.

The surface modifier has only one epoxy group or hydroxyl group, whichis a functional group, at one terminal end. The functional group is apolar group, has a high affinity to the surfaces of the inorganic oxideparticles which are polar, that is, hydrophilic, and can bond to thesurfaces of the inorganic oxide particles which are polar, that is,hydrophilic. Meanwhile, the dispersion medium of the inorganic oxideparticles is a hydrophobic solvent, has a low affinity to the functionalgroup of the surface modifier, and does not react with the functionalgroup of the surface modifier. Therefore, the functional group of thesurface modifier and the surfaces of the inorganic oxide particleswithdraw each other, and can be selectively bonded.

In addition, since the surface modifier has only one functional group,and the functional group is used for bonding with the inorganic oxideparticles, there is no functional group present on the opposite side(the other end side of the surface modifier) of the functional group ofthe surface modifier, that is, the siloxane skeleton portion. Inaddition, the siloxane skeleton portion is hydrophobic, and has a highaffinity to the hydrophobic solvent, but has little affinity to theinorganic oxide particles.

As such, by making the surface treatment agent react with the inorganicoxide particles in the hydrophobic solvent by using the surface modifierwhich is a polydimethylsiloxane-skeleton polymer having one functionalgroup at one terminal end, the functional group (polar group) of thesurface modifier is selectively oriented and bonded to the inorganicoxide particles, and the other end side is dispersed in the hydrophobicsolvent, thereby forming a shape wherein the other end side is facingthe outside of the inorganic oxide particles. Therefore, the functionalgroup portion of the surface treatment agent bonds to the inorganicoxide particles, and the other end forms a shape in which the other endis separated from the inorganic oxide particles, so that the surfacetreatment agents are radially arranged.

Since the surface modifier modifies the surfaces of the inorganic oxideparticles in the above manner, it becomes possible to modify asufficient amount of the surface modifier on the surfaces of theinorganic oxide particles in order to provide compatibility to thesilicone resin. In addition, the siloxane skeleton portion which existsat the other end of the surface modifier so that the siloxane skeletonportions are arranged radially away from the inorganic oxide particles,has a high compatibility with the silicone resin and favorable bondingproperties. Due to the above facts, it is possible to uniformly dispersethe inorganic oxide particles in the silicone resin and to form afavorable composite composition.

That is, it becomes possible to realize efficient modification of thesurfaces of the inorganic oxide particles for the first time by usingthe surface modifier composed of a polydimethylsiloxane-skeleton polymerhaving one functional group at one terminal end and using thehydrophobic solvent.

Meanwhile, in a case in which a polyfunctional polysiloxane of therelated art is used as the surface modifier, and a plurality offunctional groups exist in a dispersed manner in the polysiloxaneskeleton, the respective functional groups and the inorganic oxideparticles bond to each other, and therefore a shape is formed in whichthe polysiloxane structure does not radially separated from theinorganic oxide particles, but attaches to the surfaces of the inorganicoxide particles. Therefore, it is difficult to provide a sufficientamount of the surface modifier on the surfaces of the inorganic oxideparticles in order to provide compatibility to the silicone resin bymodification. Furthermore, in an aspect of the molecular shape, since itis difficult to make all the functional groups face the surfaces of theinorganic oxide particles, unreacted functional groups remain on thesurface modifier, and the compatibility with the silicone resindeteriorates. Therefore, it becomes difficult to uniformly disperse theinorganic oxide particles in the silicone resin.

In addition, in a case in which not one functional group but severalfunctional groups are present at one terminal end of polysiloxane, it isdifficult for all of the functional groups to reliably react with thesurfaces of the metal oxide particles. Therefore, there is a possibilitythat unreacted functional groups, that is, the remaining of the polargroups may provide an adverse influence such as occurrence of gelationor a phenomenon in which a composite composition becomes clouded, inreference to the compatibility with the silicone resin which ishydrophobic.

Meanwhile, among examples of the functional group included in thesurface modifier being used in the embodiment, that is, among examplesof terminal groups, the monoglycidyl ether-terminal end bonds with thehydroxyl group existing on the surfaces of the inorganic oxide particlesthrough ring-opening of the epoxide portion which is a part of theglycidyl group. In addition, the monohydroxy ether terminal end bondswith the surfaces of the inorganic oxide particles due to dehydrationcondensation of the hydroxyl group existing at the terminal end and thehydroxyl group existing on the surfaces of the inorganic oxideparticles.

The aforementioned bonding reaction progresses as long as the surfacemodifier and the inorganic oxide particles coexist and are heated, but acatalyst may be added in order to facilitate the progress of thereaction. For example, in the case of the monoglycidyl ether-terminalend, it is possible to select a tin compound, a titanium compound, azirconium compound, or the like as the catalyst for ring-opening of theepoxide portion. Similarly, also in the case of the monohydroxyether-terminal end, it is possible to select, a tin compound, a titaniumcompound, a zirconium compound, or the like as the catalyst fordehydration condensation. The catalyst may be used solely or incombination of two or more kinds. Meanwhile, in a case in which asubstance having a catalytic action of a tin oxide, a titanium oxide, azirconium oxide, or the like is selected as the inorganic oxideparticles, it is also possible to use the inorganic oxide particles asthe alternative of the catalyst without using a catalyst.

Here, when bonding is performed between the functional group and thesurfaces of the inorganic oxide particles, there are cases in whichwater is generated by dehydration reaction. As described below, water,which is generated during a crosslinking reaction for curing thesilicone resin, may remain in the resin and cause problems in which acomposite composition becomes clouded or the like. Therefore, suchgeneration of water is not preferable. On the other hand, water, whichis generated when the functional group of the surface modifier and thesurfaces of the inorganic oxide particles are bonded in the hydrophobicsolvent, can be readily removed outside the system, and problem is notcaused in particular.

In addition, in the surface modifier, the monoglycidyl ether-terminatedpolydimethylsiloxane does not contain a hydroxyl group, and themonohydroxy ether-terminated polydimethylsiloxane has a hydroxyl grouponly as the functional group which bonds with the inorganic oxideparticles. Therefore, after bonding to the surfaces of the inorganicoxide particles, both the surface modifiers have a molecular structurethat does not contain a hydroxyl group.

Therefore, water is not generated by a dehydration reaction, andshrinkage of the obtained transparent composite is small, even whencuring of the composite composition is made to progress due to thecrosslinking reaction between the polysiloxane of the surface modifierand the silicone resin, such as, for example, a crosslinking reaction inwhich a methyl group (—CH₃) which bonds to Si of a polysiloxane and amethyl group which bonds to Si of the silicone resin are crosslinkedthrough a dehydrogenation reaction using a peroxide as a catalyst.Therefore, since pores or cracks are not generated in the transparentcomposite, and the dispersibility of the inorganic oxide particles inthe cured silicone resin is favorably maintained, it is possible toobtain a defect-free transparent composite.

It is preferable that the number average molecular weight of thepolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof, which is the surface modifier, is 500 to 10000,and more preferably 1000 to 8000.

Here, the reason for limiting the number average molecular weight of thepolymer to 500 to 10000 is that, when the number average molecularweight of the polymer is less than 500, the amount of the siloxaneskeleton portion which has hydrophobic property is small, and thereforeit becomes difficult to make the inorganic oxide particles compatiblewith the silicone resin, and the transparency is not obtained when theinorganic oxide particles and the silicone resin are conjugated. On theother hand, when the number average molecular weight of the polymerexceeds 10000, the characteristics of the silicone resin is highlyaffected by the polymer, and the characteristics of the composite suchas the refractive index deteriorate.

The mass ratio of the surface modifier to the inorganic oxide particlesis preferably 5% by mass to 200% by mass with respect to the inorganicoxide particles, more preferably 5% by mass to 1500% by mass, still morepreferably 10% by mass to 100% by mass, and particularly preferably 20%by mass to 100% by mass.

Here, the reason for limiting the mass ratio of the surface modifier to5% by weight to 200% by weight is that, when the mass ratio of thesurface modifier is less than 5% by mass, the amount of the surfacemodifier is too small, and therefore it becomes difficult to make themetal oxide particles compatible with the silicone resin, and thetransparency is not obtained when the inorganic oxide particles and thesilicon resin are conjugated. On the other hand, when the mass ratio ofthe surface modifier exceeds 200% by mass, the ratio of the surfacemodifier in the composite composition or the transparent compositebecomes too large to ignore, and therefore, the characteristics of thecomposite composition and the transparent composite are highly affectedby the surface modifier, and there is a possibility that thecharacteristics deteriorate.

The surfaces modified inorganic oxide particles obtained in the abovemanner, which is modified by bonding with the surface modifier which isa polydimethylsiloxane-skeleton polymer having one functional group atone terminal end, is present together with the hydrophobic solvent whichis a treatment solvent, the surface modifier remaining unreacted, thecarboxylic acid or the amine which is the specific dispersant and isremoved from the inorganic oxide particles through substitution, and thelike.

Therefore, in order to obtain the target substance, the inorganic oxideparticles are separated from the hydrophobic solvent and are washedusing a suitable organic solvent or the like to remove the remainingsurface modifier, the specific dispersant, and the like. Here, theorganic solvent which is used for washing is a solvent which is used forremoving the remaining surface modifier, the specific dispersant, andthe like. Since the substances to be removed have polar groups, it ispreferable that the organic solvent being used is not a fullyhydrophobic solvent, but is a polar organic solvent having a certaindegree of hydrophilicity.

Thus far, a method has been described in which the surface modifierwhich is a polydimethylsiloxane-skeleton polymer having one functionalgroup at one terminal end is added to the hydrophobic solvent in whichthe inorganic oxide particles to which the specific dispersant is bondedare dispersed, and the surface modifier is substituted for the specificdispersant bonded in advance to the surface of the inorganic oxide tocombining and modifying the surface modifier to the surfaces of theinorganic oxide particles. More specific examples of this method includea method in which the surface modifier which is of apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end is added to a tetragonal zirconia dispersion fluid in whichthe carboxylic acid is coordinated on the surface thereof, furthermore,an appropriate amount of a catalyst is added, and a reflux treatment iscarried out.

Here, the catalyst may be a tin compound, a titanium compound, azirconium compound, and the like, and is appropriately selected.

After the reflux treatment, the inorganic oxide particles modified usingthe surface modifier are washed using an organic solvent, such as analcohol, to remove unreacted surface modifier, carboxylic acid detachedfrom the inorganic oxide particles, and the like to outside the system,and then the inorganic oxide particles are dried in a vacuum, wherebythe inorganic oxide particles modified using the surface modifier can beobtained.

In the following process, the inorganic oxide particles having thesurfaces modified through bonding of the surface modifier and thesilicone resin are mixed, and the composite composition of the inventioncan be obtained.

Here, the silicone resin is not particularly limited, and any siliconeresin can be used without any problem as long as the silicon resin isthe above silicone resin. However, in particular, a straight siliconeresin or a modified silicone resin can be preferably used.

The method of mixing the inorganic oxide particles modified using thesurface modifier and the silicone resin is not particularly limited, andany conventionally known method, such as mixing, various millings, orapplication of ultrasonic waves, can be selectively used.

Here, the inorganic oxide particles modified using the surface modifiercan be mixed in a particle state with the silicone resin, but it ispreferable that the inorganic oxide particles be dispersed again in ahydrophobic solvent having a high compatibility with the silicone resinbeing used, and a dispersion fluid of the inorganic oxide particles andthe silicone resin be mixed and stirred, thereby obtaining a compositecomposition. The reason is as follows. As compared to a method in whicha solvent is used, a large effort is required in a method in which theinorganic oxide particles are directly added and dispersed in thesilicone resin having a certain degree of viscosity so that theinorganic oxide particles are dispersed uniformly and particleagglomeration is prevented. On the other hand, a little effort isrequired in a method in which the inorganic oxide particles are addedand dispersed in a hydrophobic solvent having a low viscosity, and alittle effort is also required for mixing the obtained dispersion fluidand the silicone resin, since they are fluid.

In addition, in a case in which a mixture of the inorganic oxideparticles modified using the surface modifier and the silicone resin hasa high viscosity, there are cases in which problems of deterioration ofthe moldability of the transparent composite described below ordeterioration of easy handling may occur due to poor fluidity. In orderto prevent these problems, it is preferable that an appropriate solventbe added to a mixture of the inorganic oxide particles and the siliconeresin so as to decrease the viscosity of the mixture. As the solventbeing used here, a solvent in which the surfaces treated inorganic oxideparticles are well dispersed, and with which the silicone resin has ahigh compatibility is suitable is preferably used, and therefore ahydrophobic solvent can be selected.

Examples of the hydrophobic solvent that can be preferably used includearomatic hydrocarbon such as benzene, toluene, xylene, and ethylbenzeneand chlorine-containing solvents such as dichloromethane, chloroform,and carbon tetrachloride. It is possible to use one or two or more kindsof the solvents.

Accordingly, when the inorganic oxide particles and the silicone resinare mixed and stirred, it is possible to add the hydrophobic solvent atthe same time that mixing and stirring of both components start or aftermixing and stirring progresses to some extent.

As a specific method for mixing the silicone resin and the inorganicoxide particles modified using the surface modifier to obtain thecomposite composition, for example, a method can be cited wherein thewashed, dried, and modified inorganic oxide particles is dispersed againin a hydrophobic solvent, the silicone resin is further added thereto,and mixing and stirring thereof are performed.

Furthermore, it is also possible to appropriately add the hydrophobicsolvent to the obtained composite composition, and adjust the viscosityby mixing them using a mixer or the like, to produce a compositecomposition which is easy to flow and is suitably used for molding forforming a transparent composite.

It is possible to obtain the composite composition of the embodiment inthe above manner.

Here, the average dispersed particle diameter of the inorganic oxideparticles used in the method of manufacturing the composite compositionof the embodiment is preferably 1 nm or more. The reason is that, whenthe average dispersed particle diameter is less than 1 nm, the primaryparticle diameter of particles that form the dispersed particles alsobecomes less than 1 nm and therefore the crystallinity becomesinsufficient, and it becomes difficult to express particlecharacteristics such as the refractive index.

In addition, in a case in which the composite composition obtained usingthe method of manufacturing the composite composition of the embodimentneeds to have transparency, the average dispersed particle diameter ofthe inorganic oxide particles being used is preferably 20 nm or less.The reason is that, when the average dispersed particle diameter exceeds20 nm, the influences of Rayleigh scattering become large, and there isa possibility that the transparency of the composite compositiondeteriorates.

[Transparent Composite]

The transparent composite of the embodiment is a transparent composite,wherein inorganic oxide particles having an average dispersed particlediameter of 1 nm to 20 nm is dispersed in a silicone resin, and has aspecific shape. The surface of the inorganic oxide particles aremodified through bonding of one functional group of a surface modifierwhich is a polydimethylsiloxane-skeleton polymer having one functionalgroup at one terminal end to said surface.

Here, the “having a specific shape” means that the transparent compositedoes not have an irreversible deformability such as those of a liquidphase, a gel phase, or the like, and can maintain a constant shape inaccordance with the purpose or method of use. That is, this means thatthe transparent composite does not have fluid characteristics, and thetransparent composite has a solid phase which, in general, does notsubstantially deform, or has an elastic deformability (shape-returningproperties) of a rubber state or the like. The above expression does notmean the limitation of the shape.

Here, the transparent composite obtains a state having a specific shapeby increasing the polymerization degree or the crosslinking degree ofthe silicone resin or increasing polymerization or the number ofcrosslinkings between the silicone resin and the siloxane structure ofthe surface modifier in the composite composition. Therefore, therespective components that constitute the transparent composite, thatis, the two components which are the silicone resin and the inorganicoxide particles wherein the surfaces thereof has been modified by thesurface modifier composed of a polydimethylsiloxane-skeleton polymerhaving one functional group at one terminal end are the same as thecomponents of the above composite composition.

Meanwhile, the transparent composite basically does not include ahydrophobic solvent, and the amount is extremely small if thehydrophobic solvent is included in the composite.

Since the transparent composite has a high compatibility between theinorganic oxide particles and the silicone resin which form thetransparent composite, and the affinity between both components is high,and the dispersibility of the inorganic oxide particles in the siliconeresin is favorable. Therefore, there is no case in which opticalcharacteristics, mechanical characteristics, thermal stability, and thelike deteriorate due to the occurrence of phase separation between theinorganic oxide particles and the silicone resin or the occurrence ofaggregation of the inorganic oxide particles, and therefore it ispossible to maintain favorable characteristics.

In addition, no hydroxyl group remains in the surface modifier thatmodifies the inorganic oxide particles as described above. Due to theabove fact, when the composite composition is cured when the transparentcomposite is formed, water is not generated due to a dehydrationreaction during curing, and, furthermore, a shrinkage of the obtainedtransparent composite is small. Therefore, pores or cracks are notgenerated in the transparent composite. Additionally, since no chelatingagent is used in the composite composition which is a material forforming the transparent composite, there is no possibility that thetransparent composite is colored.

In addition, the average dispersed particle diameter of the inorganicoxide particles included in the transparent composite is 20 nm or less.Therefore, the occurrence of Rayleigh scattering, whose influencesincrease when the average dispersed particle diameter exceeds 20 nm, issuppressed at a low level, and there is no case in which thetransparency of the transparent composite deteriorates.

As such, since the inorganic oxide particles are nanometer-sizedparticles of 20 nm or less, even in a case in which the inorganic oxideparticles are dispersed in the silicone resin so as to produce thecomposite composition or an optical material, light scattering is small,and it is possible to maintain the transparency of the compositecomposition and the optical material.

On the other hand, the average dispersed particle diameter of theinorganic oxide particles included in the transparent composite is setto 1 nm or more. Therefore, it is also possible to set the primaryparticle diameter of particles that form the dispersed particles to 1 nmor more. Therefore, deterioration of the crystallinity of the particlesis suppressed. Since the crystallinity of the inorganic oxide particlesis maintained, the characteristics of the inorganic oxide particles,such as refractive index, hardness, and heat resistance, do notdeteriorate, and thus it is possible to sufficiently obtain the effectof conjugating the inorganic oxide particles.

Here, examples of the effect of conjugating the inorganic oxideparticles are as follows.

Firstly, as the optical characteristics, control of the refractive indexof the transparent composite can be cited. Since the refractive index ofthe silicone resin is approximately 1.4, it is possible to increase therefractive index of the transparent composite by conjugating theparticles of an oxide having a high refractive index of 1.8 or more.Particularly, it is effective to conjugate inorganic oxide particleshaving a high refractive index, such as tetragonal zirconium having arefractive index of 2.15 or titanium oxide having a refractive index ofapproximately 2.6. When these high-refractive index inorganic oxides areused, for example, it is possible to increase the refractive index ofthe transparent composite to approximately 1.5 to 1.65 which isapproximately 0.1 to 0.2 higher than the refractive index of a siliconeresin itself which is a base resin. Meanwhile, with regard totransparency, when the average dispersed particle diameter of theinorganic oxide particles is set to 20 nm or less as described above,occurrence of light scattering is sufficiently suppressed at a lowlevel, and thus sufficient transparency is maintained.

Here, when low-refractive index particles such as hollow silicaparticles are conjugated, it is also possible to decrease the refractiveindex of the transparent composite.

Next, as the mechanical characteristics, improvement of the hardness ofthe transparent composite can be cited. Since an ordinary inorganicoxide has a higher hardness than the silicone resin, it is possible toincrease the surface hardness of the transparent composite throughconjugation of the inorganic oxide particles, and thus it is possible toimprove abrasion resistance and improve the dimensional accuracy of thecomposite. Particularly, since zirconium oxide has a high hardness amongoxide-based ceramics, conjugation of zirconium oxide highly improves thesurface hardness.

In addition, since the silicone resin includes silicon (Si) in theskeleton structure thereof, the silicone resin is excellent in thermalstability or chemical stability such as heat resistance or chemicalresistance compared to ordinary resins. Meanwhile, the heat resistanceof an inorganic oxide is higher than that of the silicone resin, and itis also possible to achieve high chemical stability when a material ofan inorganic oxide is selected. Accordingly, it is possible to furtherimprove the thermal stability and chemical stability of the transparentcomposite through conjugating the inorganic oxide particles.

Here, as is evident from the fact that the silicone resin has a highcompatibility with the hydrophobic solvent, the silicone resin hashydrophobic (water-repellent) properties. However, the silicone resin ishighly flexible, and has a low vapor gas barrier properties compared toother resins. Here, in the transparent composite of the embodiment, theinorganic oxide particles having high gas barrier properties areuniformly dispersed in the transparent composite, and the bondingproperties of the inorganic oxide particles with the silicone resin arehigh. Accordingly, conjugation of the inorganic oxide particlesmaintains the transparent composite in a state in which thehydrophobicity is high, and the vapor gas barrier properties are alsohigh.

As such, when high-refractive index inorganic oxide particles,particularly, zirconium oxide is conjugated with the silicone resin, itbecomes possible to increase the refractive index of the obtainedtransparent composite to, for example, approximately 1.5 to 1.65.Furthermore, since improvement of the hardness improves the dimensionaccuracy, the degree of freedom in the design of optical elements isimproved. Therefore, for examples, it is possible for optical lenses todecrease the size and thickness, achieve integration, improve thelight-collecting efficiency, reduce the wavelength dependency of therefractive index, and the like. Therefore, it is possible to expect theimprovement in the characteristics of CCD or CMOS cameras and the like,which are devices using such optical elements, such as the achievementof the high resolution and the high sensitivity.

In addition, in a case in which the transparent composite is used as asealing material of an LED which is a light-emitting element, since thetransparent composite has a higher refractive index than a siliconeresin itself which is a conventional sealing material component, it ispossible to improve the conformity of the refractive index between thesealing material and a member having a high refractive index such as alight-emitting body and a substrate for forming a light-emitting body,which are covered with a sealing material, (the refractive index of asemiconductor material which is a light-emitting body of an LED isapproximately 2.5, and the refractive index of a light-permeablesubstrate on which a film of a semiconductor material is formed isapproximately 1.76). Therefore, internal reflection is reduced in aprocess of emitting light to outside from the light-emitting body of anLED.

Therefore, when the transparent composite of the embodiment is used fora sealing material of an LED, it can be expected that the lightextraction efficiency of the LED is improved by approximately 10% to15%, and it is possible to improve the brightness.

Furthermore, the transparent composite has high vapor gas barrierproperties. Accordingly, it is possible to suppress the deterioration oflight-emitting areas by suppressing the infiltration of moisture fromoutside, and extension of the service life of the light-emitting elementcan be expected.

In addition, in a case in which the transparent composite is used as asealing material of an organic EL, since the water vapor gas barrierproperties thereof are high, it is possible to suppress deterioration oflight-emitting areas by suppressing infiltration of moisture fromoutside.

In addition, since the inorganic oxide particles in the transparentcomposite can effectively suppress the permeability of oxide gas,similarly, it is possible to suppress deterioration of light-emittingareas.

Therefore, expansion of the service life of a light-emitting element inan organic EL can be expected by using the transparent composite of theembodiment as a sealing material of the organic EL.

[Method of Manufacturing the Transparent Composite]

The transparent composite of the embodiment can be obtained by moldingand solidifying the composite composition of the embodiment,specifically, into a specific shape. Here, the “molding and solidifyinginto a specific shape” means that the composite composition of theembodiment is not only put into a mold or the like and molded, but alsois solidified while actions and conditions for increasing the degree ofpolymerization or the degree of crosslinking are provided to thesilicone resin or the surface modifier in the simply molded compositecomposition. That is, the “molding and solidifying into a specificshape” means that a composite is formed which can maintain a constantshape which matches the purpose or method of use even after removed fromthe mold or the like. In addition, the “molding and solidifying into aspecific shape” means that steps or contents for forming the compositecan be included, and it should be understood that it is different from asimple process wherein the composite composition is merely put into amold or the like to shape the composite composition.

In the present manufacturing method, in the beginning, the compositecomposition of the embodiment is molded using a mold such as a metalmold or is made to fill a vessel of a certain shape, thereby obtaining amolded body (a molded material and an filled material) formed into adesired shape as the transparent composite. The composite compositionbeing used is preferably adjusted by adding a hydrophobic solvent or thelike to have a suitable viscosity for molding, that is, to achieve aviscosity which is suitable for providing the composition to a mold.

Next, actions, conditions, and the like with which polymerization orcrosslinking occurs to the silicone resin and the surface modifierincluded in the composite composition are provided to the molded body.The actions and conditions may be selected depending on necessity.Examples thereof include addition of temperature or heat, radiation ofultraviolet light or visible light, and the like. Due to the effectthereof, the degree of bonding (polymerization degree) between thesilicone resins or between the silicone resin and the surface modifierincreases. As a result, the molded body comes into a state in which aconstant shape can be maintained even when an external force is added tothe molded body after the molded body is removed from the mold or avessel. Hereinafter, there are cases in which the above effects andactions are described as “curing” of the composite composition.

Here, in a case in which the silicone resin or the surface modifier hasa reactive carbon double bond (C═C) in the skeleton structure thereof,there is a case in which polymerization or crosslinking progressessimply by mixing the silicone resin and the inorganic oxide particleshaving the surfaces modified and the composite composition is cured.

In addition, when a modified silicone resin having a polymerizablefunctional group is used as the silicone resin, and/or a polymerizablefunctional group is introduced in advance to the surface modifier whichis bonded to the surfaces of the inorganic oxide particles (bydenaturing the surface modifier using the functional group), it is alsopossible to cure the composite composition due to a reaction betweenfunctional groups of the silicone resins and/or between the functionalgroup of the silicone resin and the functional group of the inorganicoxide particles having the modified surfaces. For example, an acrylmodified silicone resin or an acryl modified surface modifier into whichan acryl group, which is polymerized using ultraviolet rays (UV light),is introduced as a functional group is used. Thereby, polymerizationbetween the silicone resins or bonding between the silicone resin andthe surface modifier progresses by radiation of ultraviolet rays, and,consequently, curing of the composite composition becomes possible. Themethod of curing the composite composition using the functional groupcan be selected from a variety of methods depending on the kind of thefunctional group to be introduced. Typical examples thereof include amethod in which a radical reaction initiated by heating or lightradiation is used. According to the above method, it is possible to curethe composite composition using a (polymerization) reaction using heat,a (polymerization) reaction using ultraviolet rays or the like, a(polymerization) reaction using gamma (γ) rays, a combination of aplurality of the above methods, or the like.

In the method, adding a compound which generates radicals by heating orlight radiation is also preferable.

However, in a case in which the reaction between the functional groupsis used, there are cases in which byproducts generated by bonding arenot compatible with the composite composition. Particularly, watergenerated by a dehydration reaction is not compatible with the compositecomposition. Therefore, there is a possibility that the byproducts turninto particles and are dispersed in the obtained transparent compositeso as to deteriorate the transparency. Furthermore, there is anotherpossibility that the byproducts deteriorate the bonding between theinorganic oxide particles and the surface modifier so as to causeaggregation of the inorganic oxide particles. In addition, in a case inwhich the amount of the byproducts is large, the obtained transparentcomposite significantly shrinks, and there is a possibility that poresor cracks are generated in the transparent composite.

Therefore, in the method of introducing the functional group into thesilicone resin or the surface modifier, it is necessary to paysufficient attention to the kind and amount of the functional group.

As a method of curing the composite composition by polymerization and acrosslinking reaction without using the polymerizable functional group,there is a method in which a crosslinking reaction is made to progressby radicals by adding a vulcanizing agent (crosslinking agent) such as aperoxide, and this method can be preferably used in the embodiment. Inthis reaction, for example, a methyl group (—CH₃) which bonds to Si in apolysiloxane of the surface modifier and a methyl group which bonds toSi in the silicone resin are bonded through dehydrogenation using aperoxide as a catalyst, and thus are crosslinking-bonded. Thepolymerization reaction between the silicone resins can be performedsimilarly.

According to this reaction, there is no case in which dehydrationreaction-induced water is generated during the reaction, and there is aminor shrinkage of the obtained transparent composite. Therefore, poresor cracks are not generated in the transparent composite, and it is alsopossible to favorably maintain the dispersibility of the inorganic oxideparticles in the cured silicone resin.

Particularly, the surface modifier used in the embodiment is an onefunctional group-type surface modifier, and, since the functional grouphas already been consumed for bonding with the inorganic oxideparticles, there is no functional group present in the surface treatmentagent bonded to the inorganic oxide particles, unless a particulartreatment is carried out. Therefore, in the surface modifier used in theembodiment, that is, in the monoglycidyl ether-terminatedpolydimethylsiloxane, the monohydroxy ether-terminatedpolydimethylsiloxane, or the like, it is preferable that a crosslinkingreaction be caused between the silicone resin and the surface treatmentagent bonded to the inorganic oxide particles using a method wherein adehydrogenation reaction is performed using the peroxide as a catalyst,thereby making the curing of the composite composition progress.

Examples of the vulcanizing agent used in this reaction includegenerally known organic peroxides. Examples thereof include benzoylperoxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide,parachlorobenzoyl peroxide, di-tert-butyl peroxide, tert-butylperbenzoate, and the like. It is possible to use the vulcanizing agentsolely or in combination of two or more kinds.

In the above manner, it is possible to obtain the defect-freetransparent composite of the embodiment which has excellent opticalcharacteristics, excellent mechanical characteristics, high thermalstability and high chemical stability.

Examples of the preferable embodiments according to the invention havebeen described above, but it is needless to say that the invention isnot limited to the examples. The combinations and the like of therespective configurations shown in the above examples are simplyexamples, and a variety of modifications are permitted based on designrequirements and the like within the scope of the purport of theinvention.

For example, in the embodiment, since the method of manufacturing thecomposite composition has been described with an assumption ofmanufacturing the transparent composite, the average dispersed particlediameter of the inorganic oxide particles being used was preferably setto 1 nm to 20 nm. However, in a case in which it is not necessary totake transparency into account, it is also possible to use the inorganicoxide particles having an average dispersed particle diameter outsidethe above range. For examples, in a case in which an object is toimprove the surface hardness of a molded body of the compositecomposition, it is also possible to use the inorganic oxide particleshaving an average dispersed particle diameter that is larger than 20 nm(for example, 100 nm). Even in such a case, it is possible to produce acomposite composition which enables manufacturing of a molded body whichhas a high dispersibility of inorganic oxide particles in the compositecomposition and has favorable properties, by using the method ofmanufacturing the composite composition of the invention.

EXAMPLES

Hereinafter, the invention will be specifically described using Examples1 to 7 and Comparative examples 1 to 5, but the invention is not limitedto the examples.

Example 1 Manufacturing of Zirconium Oxide Particles

A zirconia precursor slurry was prepared by adding diluted ammonia waterobtained by dissolving 344 g of 28% ammonia water (manufactured by WakoPure Chemical Industries, Ltd.) in 20 L of pure water to a zirconiumsalt solution obtained by dissolving 2615 g of zirconium oxychlorideoctahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) in 40L (liters) of pure water while stirring the mixture.

Next, an aqueous solution of sodium sulfate obtained by dissolving 300 gof sodium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.)in 5 L of pure water was added to the slurry while stirring the mixture.The amount of sodium sulfate added at this time was 30% by mass withrespect to the zirconia-converted value of zirconium ions in thezirconium salt solution.

Next, the mixture was dried at 130° C. for 24 hours in the atmosphereusing a drier so as to obtain a solid.

Next, the solid was grinded using an automatic mortar or the like, andthen fired at 500° C. for one hour in the atmosphere using an electricfurnace.

Next, the fired product was put into pure water, stirred into a slurryform, then, washed through repetition of a process of separating thesupernatant liquid using a centrifugal separator, and sufficientlyremoving the added sodium sulfate. The fired product was washed untilthe conductivity of the supernatant liquid after centrifugal separationbecame 1 mS/cm or less, and the obtained sediment was dried in a drier,thereby preparing zirconium oxide particles.

As a result of measuring the primary particle diameter of the obtainedzirconium oxide particles using a field emission type transmissionelectron microscope JEM-2100F (manufactured by JEOL Ltd.), the diameterwas 3 nm.

(Bonding of the Surface Modifier to Zirconium Oxide Particles)

Next, 85 g of toluene (manufactured by Wako Pure Chemical Industries,Ltd.) as a hydrophobic solvent and 5 g of caproic acid (manufactured byWako Pure Chemical Industries, Ltd.), which is a carboxylic acid, as aspecific dispersant were added to and mixed with 10 g of the zirconiumoxide particles, thereby bonding the caproic acid to the surfaces of thezirconium oxide particles. After that, a dispersion treatment wascarried out so as to prepare a transparent dispersion fluid of zirconiumoxide.

Next, 10 g of monoglycidyl ether-terminated polydimethylsiloxane(manufactured by Sigma-Aldrich Co. LLC.: the number average molecularweight 5000, shown by the following formula (1)) as thepolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end, which is the surface modifier, and 1000 ppm of dibutyl tindilaurate (manufactured by Wako Pure Chemical Industries, Ltd.) wereadded to 100 g of the transparent dispersion fluid of zirconium oxide,and a surface modifying treatment was carried out under heating andreflux.

(In the above formula, n represents an integer of 60 to 70.)

The solvent was removed using an evaporator from the reacted transparentdispersion fluid of zirconium oxide, and then caproic acid detached fromthe zirconium oxide particles and unreacted monoglycidylether-terminated polydimethylsiloxane were removed by repeating methanolwashing and centrifugal separation, thereby obtaining zirconium oxideparticles modified by the surface modifier of Example 1. The obtainedzirconium oxide particles modified by the surface modifier was 12 g.

(Manufacturing of a Zirconium Oxide-Silicone Resin CompositeComposition)

12 g of the obtained zirconium oxide particles modified by the surfacemodifier was dispersed again in 50 g of toluene, 4 g of dimethylsilicone (manufactured by Shin-Etsu Chemical Co. Ltd.: KF96-3000cS),which is a straight silicone resin, was added, mixed, and stirred,thereby obtaining a zirconium oxide-silicone resin composite compositionof Example 1.

(Evaluation of the Zirconium Oxide-Silicone Resin Composite Composition)

The obtained zirconium oxide-silicone resin composite composition ofExample 1 was coated on a glass substrate at a thickness of 1 mm toproduce a visible light transmittance measurement sample. In themeasurement, a spectrophotometer V-570 (manufactured by JASCOCorporation) was used, the measurement wavelength range was 400 nm to800 nm, and a glass substrate on which the composite composition was notcoated was used as a comparison sample. The average value of theobtained transmittance was used as the visible light transmittance.

As a result, the visible light transmittance was 86%.

In addition, the particle size distribution of zirconium oxide in theobtained zirconium oxide-silicone resin composite composition of Example1 was measured using a particle size distribution measurement apparatus(Microtrac 9340-UPA, manufactured by Nikkiso Co., Ltd.) to which thedynamic light scattering method is applied.

The volume average particle size (MV value) of the zirconium oxide wasobtained using arithmetic average based on the obtained distributionresult, and the value was used as the average dispersed particlediameter.

As a result, the average dispersed particle diameter was 4 nm.

(Manufacturing of a Zirconium Oxide-Silicone Resin TransparentComposite)

0.2 g of benzoyl peroxide (manufactured by Sigma-Aldrich Co. LLC.),which is a vulcanizing agent, was added to and dissolved throughstirring in the obtained zirconium oxide-silicone resin compositecomposition of Example 1, then, the solution was made to flow into amold formed with a glass substrate so as to have 1 mm thick, and heatedat 120° C. for 30 minutes to be cured, thereby obtaining a zirconiumoxide-silicone resin transparent composite of Example 1.

The content of zirconium oxide in the transparent composite was 38% byweight.

(Evaluation of the Zirconium Oxide-Silicone Resin Transparent Composite)

A cross-section of the obtained zirconium oxide-silicone resintransparent composite of Example 1 was observed using a field emissiontype transmission electron microscope JEM-2100F (manufactured by JEOLLtd.) to measure the particle diameters of 100 particles, which wererandomly selected, and the average value thereof was used as the averagedispersed particle diameter of zirconium oxide in the zirconiumoxide-silicone resin transparent composite.

As a result, the average dispersed particle diameter was 4 nm.

In addition, for the obtained zirconium oxide-silicone resin transparentcomposite of Example 1, the visible light transmittance was measured inthe thickness direction (1 mm) in a similar manner to the compositecomposition using a spectrophotometer V-570 (manufactured by JASCOCorporation).

As a result, the visible light transmittance of the zirconiumoxide-silicone resin transparent composite of Example 1 was 83%.

In addition, the obtained zirconium oxide-silicone resin transparentcomposite of Example 1 was held at 150° C. for 24 hours in theatmosphere, and whether yellowing occur was confirmed through visualobservation.

As a result, yellowing did not occur.

Example 2

A zirconium oxide-silicone resin composite composition and a transparentcomposite of Example 2 were obtained in the same manner as in Example 1except that the surface modifier of Example 1 was changed from themonoglycidyl ether-terminated polydimethylsiloxane to monohydroxyether-terminated polydimethylsiloxane (manufactured by Sigma-Aldrich Co.LLC.: the number average molecular weight 4600, shown by the followingformula (2)).

(in the above formula, n represents an integer of 60 to 70.)

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Example 2 were measured in the same manner as inExample 1. As a result, the visible light transmittance was 81%, and theaverage dispersed particle diameter was 5 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Example 2 in the same manner as in Example 1, the averagedispersed particle diameter was 6 nm. Furthermore, as a result ofobtaining the visible light transmittance in the same manner as inExample 1, the visible light transmittance was 82%. Furthermore, afterchecking whether yellowing occurs in the same manner as in Example 1,yellowing did not occur.

Example 3

A zirconium oxide-silicone resin composite composition and a transparentcomposite of Example 3 were obtained in the same manner as in Example 1except that the silicone resin of Example 1 was changed from dimethylsilicone to methyl phenyl silicone (manufactured by Shin-Etsu ChemicalCo. Ltd.: KF54-400cS).

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Example 3 were measured in the same manner as inExample 1. As a result, the visible light transmittance was 84%, and theaverage dispersed particle diameter was 4 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Example 2 in the same manner as in Example 1, the averagedispersed particle diameter was 5 nm. Furthermore, as a result ofobtaining the visible light transmittance in the same manner as inExample 1, the visible light transmittance was 82%. Furthermore, afterchecking whether yellowing occurs in the same manner as in Example 1,yellowing did not occur.

Example 4

A zirconium oxide-silicone resin composite composition and a transparentcomposite of Example 4 were obtained in the same manner as in Example 1except that the silicone resin of Example 1 was changed from dimethylsilicone to acryl modified silicone (manufactured by Gelest, Inc.:DMS-V22, 200cS).

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Example 4 were measured in the same manner as inExample 1. As a result, the visible light transmittance was 88%, and theaverage dispersed particle diameter was 5 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Example 2 in the same manner as in Example 1, the averagedispersed particle diameter was 5 nm. Furthermore, as a result ofobtaining the visible light transmittance in the same manner as inExample 1, the visible light transmittance was 85%. Furthermore, afterchecking whether yellowing occurs in the same manner as in Example 1,yellowing did not occur.

Example 5

A zirconium oxide-silicone resin composite composition and a transparentcomposite of Example 5 were obtained in the same manner as in Example 1except that the silicone resin of Example 1 was changed from dimethylsilicone to methyl hydrogen silicone (manufactured by Shin-Etsu ChemicalCo. Ltd.: KF99-20cS).

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Example 5 were measured in the same manner as inExample 1. As a result, the visible light transmittance was 82%, and theaverage dispersed particle diameter was 7 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Example 5 in the same manner as in Example 1, the averagedispersed particle diameter was 9 nm. Furthermore, as a result ofobtaining the visible light transmittance in the same manner as inExample 1, the visible light transmittance was 80%. Furthermore, afterchecking whether yellowing occurs in the same manner as in Example 1,yellowing did not occur.

Example 6

Silicon dioxide (silica) particles (manufactured by Alfa-Aesar, theprimary particle diameter: 10 nm) were used as the inorganic oxideparticles. A silicon dioxide-silicone resin composite composition and atransparent composite of Example 6 were obtained using the same methodas in Example 1 except that the silicon dioxide particles were used, andbutyl amine (manufactured by Wako Pure Chemical Industries, Ltd.), whichis an amine, was used as the specific dispersant.

The visible light transmittance and the average dispersed particlediameter of the obtained silicon dioxide-silicone resin compositecomposition of Example 6 were measured in the same manner as inExample 1. As a result, the visible light transmittance was 92%, and theaverage dispersed particle diameter was 13 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained silicon dioxide-silicone resin transparentcomposite of Example 5 in the same manner as in Example 1, the averagedispersed particle diameter was 16 nm. Furthermore, as a result ofobtaining the visible light transmittance in the same manner as inExample 1, the visible light transmittance was 90%. Furthermore, afterchecking whether yellowing occurs in the same manner as in Example 1,yellowing did not occur.

Example 7

A silicon dioxide-silicone resin composite composition and a transparentcomposite of Example 7 were obtained in the same manner as in Example 6except that the surface modifier of Example 6 was changed frommonoglycidyl ether-terminated polydimethylsiloxane to monohydroxyether-terminated polydimethylsiloxane (manufactured by Sigma-Aldrich Co.LLC.: the number average molecular weight 4600).

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Example 7 were measured in the same manner as inExample 1. As a result, the visible light transmittance was 90%, and theaverage dispersed particle diameter was 12 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Example 7 in the same manner as in Example 1, the averagedispersed particle diameter was 12 nm. Furthermore, as a result ofobtaining the visible light transmittance in the same manner as inExample 1, the visible light transmittance was 88%. Furthermore, afterchecking whether yellowing occurs in the same manner as in Example 1,yellowing did not occur.

Comparative Example 1 Reference Example 1

Zirconium oxide particles (manufactured by Sigma-Aldrich Co. LLC.)having a primary particle diameter of 50 nm were used as the inorganicoxide particles. A silicon dioxide-silicone resin composite compositionand a transparent composite of Comparative example 1 (Referenceexample 1) were obtained in the same manner as in Example 1 except thatthe zirconium oxide particles having a primary particle diameter of 50nm were used.

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Comparative example 1 (Reference example 1) were measuredin the same manner as in Example 1. As a result, the visible lighttransmittance was 11%, the composite composition became slightly turbid,and the average dispersed particle diameter was 78 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Comparative example 1 (Reference example 1) in the samemanner as in Example 1, the average dispersed particle diameter was 85nm. Furthermore, as a result of obtaining the visible lighttransmittance in the same manner as in Example 1, the visible lighttransmittance was 12%. Furthermore, after checking whether yellowingoccurs in the same manner as in Example 1, yellowing did not occur.

Comparative Example 2

A zirconium oxide-silicone resin composite composition and a transparentcomposite of Comparative example 2 were obtained in the same manner asin Example 1 except that the surface modifier was changed frommonoglycidyl ether-terminated polydimethylsiloxane having only onefunctional group at one terminal end thereof to bishydroxyether-terminated polydimethylsiloxane (manufactured by Sigma-Aldrich Co.LLC.: the number average molecular weight 5000) having a functionalgroups at both terminal ends respectively.

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Comparative example 2 were measured in the same manner asin Example 1. As a result, the visible light transmittance was 18%, andthe average dispersed particle diameter was 56 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Comparative example 2 in the same manner as in Example 1,the average dispersed particle diameter was 61 nm. Furthermore, as aresult of obtaining the visible light transmittance in the same manneras in Example 1, the visible light transmittance was 16%. Furthermore,after checking whether yellowing occurs in the same manner as in Example1, yellowing did not occur.

Comparative Example 3

A zirconium oxide-silicone resin composite composition and a transparentcomposite of Comparative example 3 were obtained in the same manner asin Example 1 except that the surface modifier was changed frommonoglycidyl ether-terminated polydimethylsiloxane having only onefunctional group at one terminal end thereof to diglycidylether-terminated polydimethylsiloxane (manufactured by Sigma-Aldrich Co.LLC.: the number average molecular weight 5000) having one functionalgroups at both terminal ends respectively.

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Comparative example 3 were measured in the same manner asin Example 1. As a result, the visible light transmittance was 23%, andthe average dispersed particle diameter was 34 nm.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Comparative example 3 in the same manner as in Example 1,the average dispersed particle diameter was 42 nm. Furthermore, as aresult of obtaining the visible light transmittance in the same manneras in Example 1, the visible light transmittance was 22%. Furthermore,after checking whether yellowing occurs in the same manner as in Example1, yellowing occurred.

Comparative example 4

A zirconium oxide-silicone resin composite composition and a transparentcomposite of Comparative example 4 were obtained in the same manner asin Example 1 except that the surface modifier was changed frommonoglycidyl ether-terminated polydimethylsiloxane having only onefunctional group at one terminal end thereof to disilanol-terminatedpolydimethylsiloxane (manufactured by Sigma-Aldrich Co. LLC.: the numberaverage molecular weight 5300) having one functional groups at bothterminal ends respectively.

The visible light transmittance and the average dispersed particlediameter of the obtained zirconium oxide-silicone resin compositecomposition of Comparative example 4 were measured in the same manner asin Example 1. As a result, the visible light transmittance was 21%, theaverage dispersed particle diameter was 51 nm, and aggregation of theparticles was considered to occur.

In addition, as a result of measuring the average dispersed particlediameter of the obtained zirconium oxide-silicone resin transparentcomposite of Comparative example 4 in the same manner as in Example 1,the average dispersed particle diameter was 55 nm. Furthermore, as aresult of obtaining the visible light transmittance in the same manneras in Example 1, the visible light transmittance was 15%. Furthermore,after checking whether yellowing occurs in the same manner as in Example1, yellowing did not occur.

Comparative Example 5

Dimethyl silicone (manufactured by Shin-Etsu Chemical Co. Ltd.:KF96-3000cS), which is a straight silicone resin and was used as thesilicone resin, which is singly used and does not include the inorganicoxide particles, and the visible light transmittance of the siliconeresin (a viscous liquid-like) itself was measured in the same manner asin Example 1.

As a result, the visible light transmittance was 93%.

The above results are summarized and shown in Table 1.

Meanwhile, with regard to evaluation of yellowing, a case in whichyellowing does not occur is given “O”, and a case in which yellowingoccurs is given “X”.

The results of evaluation showed that the composite compositions of therespective examples had favorable characteristics in which the averagedispersed particle diameter of the inorganic oxide particles was 20 nmor less, and the visible light transmittance was also 81% or more, whichdid not significantly decrease as compared with Comparative example 5(93%) which was a comparison sample. In addition, it was also found thatthe transparent composite of the respective examples have favorablecharacteristics in which the average dispersed particle diameter of theinorganic oxide particles was 20 nm or less, the visible lighttransmittance was also 81% or more which did not significantly decreaseas compared with Comparative example 5 (93%) which was a comparisonsample, and furthermore, yellowing did not occur after the heatingtreatment.

On the other hand, in Comparative example 1 (Reference example 1), theaverage dispersed particle diameter of the composite composition and thetransparent composite did not significantly increase as compared withthe primary particle diameter of the inorganic oxide particles. However,the visible light transmittance decreased. This is considered such that,because the primary particle diameter of the inorganic oxide particlesis as large as 50 nm and the primary particle diameter itself is large,the particles were liable to aggregate as compared to small primaryparticles, and therefore the average dispersed particle diameter of theinorganic oxide particles in the composite composition and thetransparent composite increased, and light scattering occurred.

In addition, in Comparative examples 2 to 4, the primary particlediameter of the inorganic oxide particles is as small as 3 nm; however,compared to this diameter, the average dispersed particle diameter inthe composite composition and the transparent composite increasedsignificantly to be 30 nm or more. Therefore, the visible lighttransmittance decreased. This is considered that because a substancehaving functional groups at both terminal ends was used as the surfacemodifier, it was not possible to sufficiently modify the surfaces of theinorganic oxide particles, the inorganic oxide particles in the siliconeresin aggregated to increase the average dispersed particle diameter,and the visible light transmittance decreased as a result of lightscattering.

Based on the above results, the availability of the invention wasconfirmed.

TABLE 1 Composite Transparent Surface composition composite Inorganicoxide modifier Average Average particles Number Functional Visibledispersed Visible dispersed Primary average group light particle lightparticle particle molecular Num- Loca- Silicone transmit- diametertransmit- diameter Yellow- Material diameter Material weight ber tionresin tance (%) (nm) tance (%) (nm) ing Example 1 Zirconium 3 PDMS-MGE5000 1 Single Dimethyl 86 4 83 4 ∘ oxide terminal silicone end Example 2Zirconium 3 PDMS-MHE 4600 1 Single Dimethyl 81 5 82 6 ∘ oxide terminalsilicone end Example 3 Zirconium 3 PDMS-MGE 5000 1 Single Methyl 84 4 825 ∘ oxide terminal phenyl end silicone Example 4 Zirconium 2 PDMS-MGE5000 1 Single Acryl 88 5 85 5 ∘ oxide terminal modified end siliconeExample 5 Zirconium 3 PDMS-MGE 5000 1 Single Methyl 82 7 80 9 ∘ oxideterminal hydrogen end silicone Example 6 Silicon 10 PDMS-MGE 5000 1Single Dimethyl 92 13 90 16 ∘ dioxide terminal silicone end Example 7Silicon 10 PDMS-MHE 4600 1 Single Dimethyl 90 12 88 12 ∘ dioxideterminal silicone end Comparative Zirconium 50 PDMS-MGE 5000 1 SingleDimethyl 11 78 12 85 ∘ example 1 oxide terminal Silicone end ComparativeZirconium 3 PDMS-BHE 5000 2 Both Dimethyl 18 56 16 61 ∘ example 2 oxideterminal Silicone ends Comparative Zirconium 3 PDMS-DGE 5000 2 BothDimethyl 23 34 22 42 x example 3 oxide terminal Silicone endsComparative Zirconium 3 PDMS-DSH 5300 2 Both Dimethyl 21 51 15 55 ∘example 4 oxide terminal Silicone ends Comparative None — None — — —Dimethyl 93 — 92 — — example 5 Silicone Surface modifier material: 1.PDMS-MGE: monoglycidyl ether-terminated polydimethylsiloxane 2.PDMS-MHE: monohydroxy ether-terminated polydimethylsiloxane 3. PDMS-BHE:bishydroxy ether-terminated polydimethylsiloxane (Comparative example 2)4. PDMS-DGE: diglycidyl ether-terminated polydimethylsiloxane(Comparative example 3) 5. PDMS-DSH: disilanol-terminatedpolydimethylsiloxane (Comparative example 4)

INDUSTRIAL APPLICABILITY

In the inorganic oxide particle-silicone resin composite composition ofthe embodiment, the compatibility between the inorganic oxide particlesand the silicone resin is high, the inorganic oxide particles and thesilicone resin are excellent in terms of conjugating properties, andcoloration is prevented. Furthermore, in the transparent compositeformed by molding and solidifying the present composite composition intoa specific shape, it is possible to obtain a composite in which phaseseparation does not occur, pores or cracks are not generated, thetransparency is excellent, and the optical characteristics, mechanicalcharacteristics, and thermal stability are excellent.

Furthermore, it is possible to obtain a transparent composite having ahigh refractive index and a high transparency by selecting zirconiumoxide, titanium oxide, or the like having a high refractive index as theinorganic oxide particles.

Therefore, the inorganic oxide particle-silicone resin compositecomposition and the transparent composite of the embodiment can bepreferably used not only as sealing materials of light-emitting diodes(LED), optical sheets such as liquid crystal display substrates, organicEL display substrates, color filter substrates, touch panel substratesand solar cell substrates, transparent plates, optical lenses, opticalelements, optical waveguides but also as elements in a variety of otherindustrial fields, and the availability of the embodiment is large.

1. A method of manufacturing a composite composition, comprising:bonding a dispersant to a surface of an inorganic oxide particle toprovide dispersibility in a hydrophobic solvent to the inorganic oxideparticles, and then dispersing the inorganic oxide particle in ahydrophobic solvent; substituting the dispersant bonded to the surfaceof the inorganic oxide particle with a surface modifier, which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof, in the hydrophobic solvent in which the organicoxide particles are dispersed to bond the functional group of thepolydimethylsiloxane-skeleton polymer to the surface of the inorganicoxide particle; and conjugating a silicone resin and the inorganic oxideparticle obtained in the previous step, wherein the surface thereof ismodified by bonding the polydimethylsiloxane-skeleton polymer having onefunctional group at one terminal end thereof, to obtain a compositecomposition.
 2. The method of manufacturing a composite compositionaccording to claim 1, wherein the surface modifier includes one or twokinds selected from monoglycidyl ether-terminated polydimethylsiloxaneand monohydroxy ether-terminated polydimethylsiloxane.
 3. The method ofmanufacturing a composite composition according to claim 1, wherein thedispersant which is used to be bonded to the surface of the inorganicoxide particle is an organic acid compound or an organic base compound.4. The method of manufacturing a composite composition according toclaim 1, wherein the silicone resin is a straight silicone resin or amodified silicone resin.
 5. A composite composition comprising aninorganic oxide particle having an average dispersed particle diameterof 1 nm to 20 nm and a silicone resin, wherein one functional group of asurface modifier which is a polydimethylsiloxane-skeleton polymer havingone functional group at one terminal end is bonded to the surface of theinorganic oxide particle to modify the surface.
 6. A transparentcomposite, wherein an inorganic oxide particle having an averagedispersed particle diameter of 1 nm to 20 nm is dispersed in a siliconeresin, and the surface of the inorganic oxide particle is modified bybonding one functional group of a surface modifier, which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end thereof, to the surface of the inorganic oxide particle. 7.A manufacturing method of a transparent composite, comprising: moldingand solidifying the composite composition according to claim 5 to obtainthe transparent composite.
 8. The method of manufacturing a compositecomposition according to claim 1, wherein the inorganic oxide particleis a particle made of a material selected from zirconium oxide, titaniumoxide, silicon oxide, aluminum oxide, iron oxide, copper oxide, zincoxide, yttrium oxide, niobium oxide, molybdenum oxide, indium oxide, tinoxide, tantalum oxide, tungsten oxide, lead oxide, bismuth oxide, ceriumoxide, antimony oxide, germanium oxide, tin-doped indium oxide, andyttria-stabilized zirconia.
 9. The method of manufacturing a compositecomposition according to claim 1, wherein the manufactured compositecomposition comprises the inorganic oxide particle having an averagedispersed particle diameter of 1 nm to 20 nm and the silicone resin, andwherein one functional group of the surface modifier which is apolydimethylsiloxane-skeleton polymer having one functional group at oneterminal end is bonded to the surface of the inorganic oxide particle tomodify the surface.
 10. The composite composition according to claim 5,wherein the silicone resin is a straight silicone resin or a modifiedsilicone resin.
 11. The composite composition according to claim 5,wherein the inorganic oxide particle is a particle made of a materialselected from zirconium oxide, titanium oxide, silicon oxide, aluminumoxide, iron oxide, copper oxide, zinc oxide, yttrium oxide, niobiumoxide, molybdenum oxide, indium oxide, tin oxide, tantalum oxide,tungsten oxide, lead oxide, bismuth oxide, cerium oxide, antimony oxide,germanium oxide, tin-doped indium oxide, and yttria-stabilized zirconia.12. The transparent composite according to claim 6, wherein theinorganic oxide particle is a particle made of a material selected fromzirconium oxide, titanium oxide, silicon oxide, aluminum oxide, ironoxide, copper oxide, zinc oxide, yttrium oxide, niobium oxide,molybdenum oxide, indium oxide, tin oxide, tantalum oxide, tungstenoxide, lead oxide, bismuth oxide, cerium oxide, antimony oxide,germanium oxide, tin-doped indium oxide, and yttria-stabilized zirconia.